title: The effects of pre-incubation period and norharman on the mutagenic potency of 4-dimethylaminoazobenzene and 3'-methyl-4-dimethylaminoazobenzene in S. typhimurium.
abstract: The effects of the co-mutagen norharman on the mutagenicity of the rodent liver carcinogens 4-dimethyl-aminoazobenzene (DAB) and 3'-methyl-4-dimethyl-aminoazobenzene (3'-MeDAB) have been evaluated using the Ames Salmonella mutation assay. A period of pre-incubation was found to be necessary in order to detect DAB as a mutagen and to increase the initially weak response observed for 3'MeDAB; maximum responses were seen after 1 h pre-incubation in each case. The co-mutagenic properties of norharman were at their maximum for both azo-dyes in the direct plate-incorporation assay. Pre-incubation of either compound with norharman for increasing periods of time resulted in a decrease in potentiation, until after 1 h, an inhibition of mutagenicity was observed.
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D002243:Carbolines; D006247:Harmine / Q000031:analogs & derivatives / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008749:Methyldimethylaminoazobenzene / Q000633:toxicity*; D009153:Mutagens; D051381:Rats; D011919:Rats, Inbred Strains; D012486:Salmonella typhimurium / Q000235:genetics*; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors; D004124:p-Dimethylaminoazobenzene / Q000031:analogs & derivatives* / Q000633:toxicity*
chemical_list: D000470:Alkaloids; D002243:Carbolines; D009153:Mutagens; D006247:Harmine; D008749:Methyldimethylaminoazobenzene; C010262:norharman; D004124:p-Dimethylaminoazobenzene